Effects of a layered double hydroxide (LDH) on the photostability of wood flour/polypropylene composites during UV weathering

Abstract

In this study, a kind of layered double hydroxide, MgAl-CO 3 -LDH, was synthesised and its effects on the photostability of wood flour/polypropylene (WF/PP) composites during weathering were investigated. WF/PP composites with different LDH loading levels were prepared and tested in a QUV accelerated weathering tester for a total 960 h. The surface color, surface gloss, and flexural properties of the composites were tested, accompanied by characterizations using SEM, ATR-FTIR, and TG. The results indicated that (1) the flexural properties of the LDH-loaded composites were improved; (2) the composites containing LDH showed less discoloration, fewer surface cracks, and less loss of flexural strength and modulus than the control group; (3) LDH played a positive effect on alleviating the photooxidation process of WF/PP composites, confirming its UV-shielding effect; (4) LDH enhanced the thermal stability of the composites before and after weathering.

Synthesis of 5‐sulfosalicylic acid‐intercalated layered double hydroxide and its effects on wood flour/polypropylene composites during accelerated UV weathering

“…The FTIR spectra of LDH, SA, and LDH‐SA are shown in Figure (b). The band around 3425 cm −1 shown in the spectrum of LDH was assigned to the stretching vibration of the hydroxyl groups of LDH layers and interlayer water molecules . The sharp band observed at 1364 cm −1 corresponded to the ν 3 stretching vibration of group, while the band at 450 cm −1 was the signal of OMO vibrations in the LDH layers .…”

“…The band around 3425 cm 21 shown in the spectrum of LDH was assigned to the stretching vibration of the hydroxyl groups of LDH layers and interlayer water molecules. 27 The sharp band observed at 1364 cm 21 corresponded to the m 3 stretching vibration of NO 2 3 group, while the band at 450 cm 21 was the signal of OAMAO vibrations in the LDH layers. 22 The spectrum of SA exhibited several distinctive bands, for example, the absorbance at 3490 cm 21 from the aromatic CAOAH, 1670 and 1376 cm 21 from the vibration of ACOO 2 , 1175 and 1040 cm 21 from the characteristic absorption band of SO 2 3 .…”

“…The general formula of LDH can be represented by [M 1− x 2+ (OH) 2 ] x + A x / m n − · n H 2 O, in which M 2+ and M 3+ are divalent and trivalent metallic cations, respectively, x is normally between 0.2 and 0.4, and A n − symbolizes various organic or inorganic anions, n is the number of water molecules located in the interlayer region . Previous studies have reported that LDH can inhibit the photo‐oxidation of asphalt and WPCs during weathering . In addition, owning to the ready exchangeability of their interlayer anions, several UV absorbers have been intercalated into LDH with a supramolecular layered structure .…”

“…25 Previous studies have reported that LDH can inhibit the photo-oxidation of asphalt and WPCs during weathering. 26,27 In addition, owning to the ready exchangeability of their interlayer anions, several UV absorbers have been intercalated into LDH with a supramolecular layered structure. [28][29][30] After intercalation, both the thermal stability and photostablity of these guest anions within the interlayer space of LDH have been markedly improved.…”

Routes to halogen‐free flame‐retardant polypropylene wood plastic composites

“…32 For all investigated materials, signals corresponding to volatiles formed during PP decomposition were observed at frequencies of 2800 to 3000 cm −1 , and in the fingerprint region at 1300 to 1400 and 900 cm −1 , corresponding to C─H stretching frequencies. 46 Thus, EG, APP, and ATH flame retardants had an effect on the amount, but a negligible effect on the kinds of volatile products liberated upon…”